GetSunScore Analysis: Solar Irradiance
Definition and Solar Context
Solar irradiance is sunlight power received per unit area at a given moment. It is important to solar production modeling, but GetSunScore's current calculator uses committed annual PVWatts production yields rather than an irradiance value entered by the visitor.
The PVWatts V8 city-yield snapshot uses an NSRDB weather dataset and the same modeled reference system for each supported city. Its annual AC output is a city reference, not a measurement of a specific roof.
What Does Solar Irradiance Mean?
Solar irradiance is quantified in watts per square meter (W/m²). Global Horizontal Irradiance (GHI) is one way to describe sunlight on a horizontal surface; actual panel output also depends on panel orientation, equipment, temperature, and losses.
Irradiance accumulated over time becomes an energy-per-area measure, often expressed in kWh/m²/year. It is related to, but not interchangeable with, the AC electricity output of a PV system.
Why Irradiance Matters in Solar Savings Modeling
The current calculator starts with a PVWatts annual AC yield per installed kW for the selected city. It applies scenario production factors and combines modeled generation with a Texas statewide EIA electricity-rate baseline.
Solar resource helps explain regional yield differences, but roof shade and design can change actual output. The calculator's city reference is not a property-specific solar assessment; see the methodology for its limits.
How Solar Irradiance Applies in Texas
Solar resource differs across Texas. The committed PVWatts snapshot represents 15 supported cities using one consistent reference system; it does not rank every Texas location or assess a homeowner's roof.
PVWatts annual yields provide a location-specific production reference. Electricity-market arrangements, including REP export terms where applicable, are separate from sunlight and are not determined by irradiance alone.
Frequently Asked Questions
Solar irradiance measures the power of sunlight reaching a specific location. Higher irradiance means more solar energy available for conversion. It is the foundational production variable in any solar savings estimate.
For each supported Texas city, GetSunScore uses a committed NLR PVWatts V8 annual AC yield per installed kW. The calculator combines that yield with system-size and scenario assumptions; it does not take a roof-level irradiance measurement or apply a local utility tariff.
Yes. Solar resource varies by location. GetSunScore's supported cities have distinct PVWatts annual yield references, but those city reference points do not describe the sunlight or shade on an individual roof.
Not exactly. Irradiance is a power measurement (W/m²), while Peak Sun Hours represent the equivalent number of hours per day at peak irradiance (1,000 W/m²). See the Peak Sun Hours glossary entry for a detailed explanation of how these concepts relate.
GetSunScore uses a committed NLR PVWatts V8 city-yield snapshot, generated with an NSRDB weather dataset and a common reference system. The calculator consumes annual AC yields from that snapshot, not direct NSRDB irradiance values.
Current city yields come from a versioned NLR PVWatts snapshot using NSRDB weather data. The calculator uses an EIA Texas rate baseline, not a household tariff. See data sources for provenance; results are non-binding estimates.